Hey Tommyjoking
I didn't build that wire feed, originally I did scavange one from an old Sciaky automated tig welder but it burnt out after a month of use (it was close to 40 years old though). I was stuck and found this little unit online from arczone, I paid about 1100 canadian for it shipped in. It's from a mig welder and I think if you new a bit more about electronics then myself you could make it work yourself.
The hardest thing oddly enough was coming up with a good simple one way purge valve, I tried using flow meters thinking that I could measure the argon/air flow coming out of the chamber. I found that the metal ball in the flow meter actually took to much pressure to release and it would push the extra set of gloves right out and you could really feel it on your gloves. Without the one way valve every time you pull your hands out a little you draw air back into the box and contaminate it.
Jim